Hello all
Is there such a thing as an a/c conversion kit (r12 to 134a). I have an 87 Brougham. The system was opened by the previous owner, and the shop wants $187.00 to convert it. Sounds a little crazy to me.

The Ape Man

05-20-06, 08:32 PM

Hello all
Is there such a thing as an a/c conversion kit (r12 to 134a). I have an 87 Brougham. The system was opened by the previous owner, and the shop wants $187.00 to convert it. Sounds a little crazy to me.

Wall Mart sells them here locally. Comes with oil charge and valve conversion hardware also. Original R-12 oil charge is left in place and additional 134 oil is added. If your system has been opened it will need to be evacuated. A high vacuum needs to be drawn in order to boil any water off and remove atmospheric pressure from system. R-134 will not cool as well as R-12 in an R-12 designed system. The condensor design is different in OEM R-134 vehicles. R-134 works great with the proper condensor and only so-so with an R-12 design condensor. There is no magic that will make the system cool as well as R-12. R-134 molecules are physically smaller than R-12 and will leak through porous hoses faster. In practice this is usually not a big deal. O rings don't care about 134 verses 12. That idea is based on availability of so called R-134 O rings. Makes no difference.
AC service mis-information is available wholesale.

johndfw

05-21-06, 06:54 PM

Thanks for the info Ape Man

Johnny Bravo

05-21-06, 09:28 PM

Hello all
Is there such a thing as an a/c conversion kit (r12 to 134a). I have an 87 Brougham. The system was opened by the previous owner, and the shop wants $187.00 to convert it. Sounds a little crazy to me.
$187 may not be that crazy after all. Here in NJ they get at least $60, and up, just to re-charge 134A systems.
The conversion kits are a joke. If you just want to squeeze one more season out of the car, then maybe it might be worth trying.

However, if you plan on keeping the car the accumulator should be replaced with a new 134A compatible unit, the old R12 oil drained from the compressor, all the seals replaced with HBNR type, and the system evacuated and charged.
If the shop will do all the above, $187 is reasonable.

The Ape Man

05-21-06, 09:48 PM

The only justification for replacement of a working accumulator is if the condition of dessicant is in doubt. The accumulator on a C.C.O.T. post '76 Cadillac is just a tank. No magic inside. Nothing to wear out except the dessicant pack.
Draining R-12 oil from the compressor during conversion is a complete waste of time and will not gain anything. 134 compatible oil just needs to be added for the conversion.
O-rings on R-12 systems work fine in practice with R-134A. Some O-rings come with new part numbers and/or green powder. They are the same material used since the late 70's.
I've personally done somewhere around 75 134A conversions on many different brands of cars. The first one was done over 10 years ago and lasted for the remaining 6 years I owned that vehicle. Topped it off once. Conversion is no big deal if the system is in good shape to begin with. You only need to start changing things when they are broken.
These conversions provide marginal cooling at best. Here in the Northeast the humidity is high when the temp goes up. Other parts of the year, the system will not be used at all. Non use can be a problem. AC systems need to be working 100% here.

Johnny Bravo

05-22-06, 12:56 AM

The only justification for replacement of a working accumulator is if the condition of dessicant. . Nothing to wear out except the dessicant pack.
Draining R-12 oil from the compressor during conversion is a complete waste of time and will not gain anything. 134 compatible oil just needs to be added for the conversion.
O-rings on R-12 systems work fine in practice with R-134A. Some O-rings come with new part numbers and/or green powder. They are the same material used since the late 70's.
I've personally done somewhere around 75 134A conversions on many different brands of cars. These conversions provide marginal cooling at best. . .
Those suggestions may explain why your conversions yielded marginal cooling performance.:Poke: A 134a converted system won't equal the cooling power of R12, but if done right it can get pretty close.
For example, I did 134a conversion an 1984 Olds Cutlass once, cheapo rebuilt compressor, new accumulator, new ester oil, etc. The vent temps on that car would consistently get down into the 38 degree range on even the hottest of days.

Without draining the compressor, and replacing the accumulator there's no way to know how much oil is actually in the system. Consequently, excessive oil will cause reduced efficency, (i.e. marginal cooling) especially in 134a systems. Insufficient oil can lead to compressor failer. Additionally, if the system had been left opened for any lenght of time the accumulator dessicant may be moisture saturated.
I disagree also about the o-rings as well. Suffice it to say if the seals are replaced, why not use the HBNR green o-rings and be done with it?:confused: There are lots of good reasons not to cut corners. The parts are inexpensive and it doesn't take much time to remove and drain the compressor and pop in a new accumulator/orifice tube.

The Ape Man

05-22-06, 03:53 AM

Sorry but a few ounces of refigerant oil won't make any difference in the system's ability to remove heat. The rest might be good salesmanship but that's about it. The real reason an R-12 system doesn't work as well with 134 is the condensor design. A crossflow condensor is needed to make 134 work properly. All vehicles originally using 134 have one and all vehicles originally with R12 don't.

davesdeville

05-22-06, 05:02 AM

Would it be feasable to retrofit a crossflow condensor into an R12 system? AC is one thing I've never quite understood.

johndfw

05-22-06, 09:39 AM

Hey guys
I found a kit, $37.00. I also found that the connector at the back of the compressor has no O rings. I'll have to replace them before I attempt a recharge.
Later

Johnny Bravo

05-22-06, 04:55 PM

Would it be feasable to retrofit a crossflow condensor into an R12 system? AC is one thing I've never quite understood.
I used a so-called GM "high efficiency" condensors on retrofit I did on on another car of mine. Unfortunately, the vent temps never got nearly as cold as the other retrofitted car with the stock condensor. Big waste of money in my opinion.
If you're not familiar with the A/C, don't have gauges and the know how to use them, it will all be guess work. Furthermore, the retrofit kit, plus a few cans of 134a refrigerant alone will probably cost close to $80, and if you have to pay a shop to evacuate the system that could be another $40-$50. I'd suggest you bite the bullet, bring it to an A/C shop in your area and let them handle it. They will probably offer a warranty on their work also.

Regarding to the oil issue, excessive oil in a 134a system will definetly affect cooling efficiency. Also, there's more to getting the most out of 134a than the condensor. Compressor design is a big factor as well.

johndfw

05-22-06, 07:20 PM

Hey
Does anyone know what the pressure readings should be? I read on another sight that there should be about 45 on the low side and 150 on the high.
Does that sound about right?

The Ape Man

05-22-06, 08:24 PM

Pressure readings vary depending on ambient temp, humidity, compressor RPM and a few other things. It isn't as simple as looking for a specific pressure.

R-134 condensors are crossflow types. Picture a radiator with a tank at each end. The tubes which join them are only a few feet long and connect in parallel. R-12 condensors are quite similar to what you see on a refigerator. They use 1 long skinny tube which criss crosses throughout the fins. 2 totally different concepts. Yes, it would be a good idea to use a crossflow type in order to take advantage of 134's potential.